This invention is in the field of covers for holes, and more particularly deals with a locking cover for temporary use in a ground hole such as a post hole or the like.
In many situations, such as construction sites or the like, excavations are undertaken which yield various vertical tubular holes in the ground. These might be drilled, augered or hydro-excavated.
The problem of safety presents itself with respect to these holes, when the construction site needs to be closed up for the day or the work crew needs to leave the hole unattended for some time and they wish to cover up the hole or close the hole for safety purposes. In some cases, the construction site might just be taped or fenced off or the hole covered with a piece of wood or the like, but these conventional methods have their limitations. Firstly, persons or vandals can uncover these holes and leave them open. The open hole is a hazard to anyone walking in the vicinity, as the can fall in the hole and injure a limb, or in the case of small children they might even fall into a larger hole. Safety regulations thus require the closure of these holes. A construction crew working on a series of holes, particularly in close vicinity to a school or the like, may find that they have to have extra people on staff to watch the holes or require some method of safely and conveniently locking those holes closed until they wish to return and complete the work and fill the hole back in.
Numerous attempts have been made in the art to provide covers for such holes. U.S. Pat. No. 5,979,117 to Fuller, xe2x80x9cHole Locking Devicexe2x80x9d, is one such device. This device is limited in its utility, however, since the telescoping cylindrical sections of that device need to be selected to correspond to the internal diameters of different holes in which the device is to be used. As such, it is difficult to manufacture a single universal size of that device, and it will likely take more than one individual to manipulate such a device into position in a hole.
Another effort of interest is disclosed in U.S. Pat. No. 4,101,154 to Kagstrom for a xe2x80x9cLocking Device for Well Covers and the Likexe2x80x9d. That disclosure relates to a device for locking the lid or cover in place on a well casing or the like. That device would be of only limited utility in anything but a pipe casing, since it is designed to operate within smooth pipe walls. The locking arms of that device would not properly handle an uneven hole wall. As well, that device has other limitations insofar as it allows for the limited raising of the cover from the top of the hole being covered. When actuating the Kagstrom device by placing it into a well, the device does not pull the lid down onto the hole. This limited degree of play could still allow for mischief or mishap.
There is a need for a secure and simple device to be used to lock and cover excavation holes, such as fence post holes, pile holes, hydro-excavation holes, and the like to prevent people, especially children, from falling in. Ideally, the apparatus used to lock the cover in place over the hole will also pull the cover down into the earth such that the hole is completely locked.
It is the object of the present invention to provide a portable locking ground hole cover for use on construction sites or the like which can be easily installed and removed by a minimum number of people, and which is easier and less costly to manufacture than those known in the art.
Further it is the object of the present invention to provide a locking ground hole cover that in addition to locking a cover plate over a hole by resting it in place on the ground surface over the hole, the action of locking the ground hole cover into position also exerts downward force on the cover adding to the strength of the lock.
The invention, a locking hole cover for use in a hole, the hole having an opening mouth and walls accomplishes these objects comprising substantially a cover plate having a lower surface and an upper surface; a plurality of wall-engaging tensioning arms, each the wall-engaging tensioning arm being hingably attached to the cover plate at a point below the lower surface, the unhinged end of each the tensioning arm, being a wall-engaging end, extending generally away from the cover plate; and a spreading apparatus engaging the tensioning arms such that when the spreading apparatus is moved towards the cover plate the wall-engaging ends of the tensioning arms will be forced outwards, and when the spreading apparatus is moved away from the cover plate the wall-engaging ends of the tensioning arms will be pulled inwards; and a shaft extending downwards from the lower surface of the cover plate and engaging the spreading apparatus such that the movement of the shaft will cause the movement of the spreading apparatus either towards or away from the cover plate.
Several methods of engagement could be used between the cover plate, the shaft and the spreading apparatus to ensure the proper movement of the tensioning arms. In one embodiment the shaft is slidably attached through the cover plate and the spreading apparatus is fixedly attached to the shaft, such that movement of the spreading apparatus towards or away from the cover plate is actuated by pulling or pushing the shaft from the upper surface of the cover plate.
In another embodiment the shaft is rotatably attached to the cover plate such that the shaft can be rotated from the upper surface of the cover plate, the shaft engaging the spreading apparatus such that rotation of the shaft will cause movement of the spreading apparatus either towards or away from the cover plate. Specifically, it is contemplated that the portion of the shaft engaged by the spreading apparatus throughout the range of its movement towards or away from the cover plate is threaded, and engages a corresponding threaded receptacle passing through the spreading apparatus.
The spreading apparatus might be a rigid member slidably engaging each tensioning arm. The rigid member could slidably engage each tensioning arm by way of an aperture at each end of the rigid member through which apertures the tensioning arms slidably pass. The rigid member might be perpendicular to the axis of the shaft.
Alternatively, the spreading apparatus could comprise a plurality of spreading arms hingably attached to each other at one end at which end the shaft will be engaged, and the free end of each the spreading arm is hingably attached to a midpoint of a corresponding tensioning arm. The spreading arms might be attached to reflective points on each the tensioning arm, defining a parallelogram, although that would not be necessary. Otherwise, the free end of each the spreading arm could also be hingably attached to a wall-engaging end of a corresponding tensioning arm.
The spreading apparatus and the tensioning arms could be locked in position by locking the shaft in position relative to the cover plate.
The tensioning arms could either be attached directly to the lower surface of the cover plate, or the cover plate might further include an arm extension extending downwards from the lower surface of the cover plate the tensioning arms are hingably attached.
Wall-engaging adapters could be attached at the wall-engaging ends of the tensioning arms, to increase the traction between the tensioning arms and the walls of the hole. Various types of wall-engaging adapters could be used depending upon the type of surface of the hole wall. For example, different adapters could be used for rock, hard soil, clay, sand or the like. These adapters could be rendered removable so that the versatility of the device is again improved and the apparatus can be easily adjusted for different soil conditions.
In order to make the device even more universal, extenders could be used in place of or as part of wall-engaging adapters. Extenders could be used to extend the reach of the tensioning arms away from the shaft so that the device could be used in wider holes.
In a situation where the cover plate is not large enough to cover the mouth of a larger hole, and to increase the versatility and universality of the device, the device might also include an adapter plate for placement between the mouth of the hole and the cover plate, the adapter plate being larger than the mouth of the hole and having an aperture extending therethrough, the aperture being smaller than the cover plate and large enough to allow the remainder of the hole cover attached to the cover plate to pass through the aperture.
Cover plates of various cross-sectional profiles could be used. In addition to a flat cover plate, it is particularly contemplated that a convex plate could be used. The outer edge of the convex cover plate could then bite into the soil surface around the hole when the cover plate was pulled down by the remainder of the apparatus as the tensioning arms grabbed the walls of the hole.
The shaft extends through the arm extension, where present. In such a case, the shaft and the arm extension could be hingably attached to the lower surface such that the cover plate has a limited range of movement in directions away from perpendicular to the remainder of the apparatus, while maintaining its attachment to the remainder of the apparatus.